This invention relates to methods of fabricating semiconductor light emitting devices and resulting structures, and more particularly to methods of fabricating semiconductor Light Emitting Diodes (LEDs) and resulting structures.
Semiconductor LEDs are widely known solid-state lighting elements that are capable of generating light upon application of voltage thereto. LEDs generally include a diode region including therein an n-type layer, p-type layer and a p-n junction. An anode contact ohmically contacts the p-type layer and a cathode contact ohmically contacts the n-type layer.
LEDs generally are fabricated in wafer form, wherein an epitaxial region, including the diode region, is epitaxially formed on a substrate, such as a sapphire, silicon, silicon carbide, gallium arsenide, gallium nitride, etc. growth substrate. The diode region may be fabricated, for example, from silicon carbide, gallium nitride, gallium phosphide, aluminum nitride and/or gallium arsenide-based materials, and/or from organic semiconductor-based materials.
After the epitaxial region is fabricated, contacts may be formed on the substrate and/or on the epitaxial region, to ohmically contact the p-type layer and the n-type layer. The contacts generally include one or more metal layers and may also include transparent conductive layers, such as indium tin oxide.
After contact fabrication, the wafer is diced or singulated into individual LEDs or individual groups of LEDs. Dicing or singulation generally is a two-step process. First, scribe lines are formed on the wafer. Then, the wafer is cleaved or broken along the scribe lines using a fracturing machine.
Scribing originally was performed by a diamond scribing tool. However, since many of the substrate wafers are extremely hard, the use of mechanical scribing tools may adversely impact the throughput, yield, reliability and/or performance of the LEDs. Accordingly, lasers have emerged as a scribing tool. Note, for example, U.S. Patent Application Publication 2008/0242056 to Sercel et al. entitled System and Method for Cutting Using a Variable Astigmatic Focal Beam Spot and U.S. Pat. No. 6,992,026 to Fukuyo et al., entitled Laser Processing Method and Laser Processing Apparatus. Also note, for example, U.S. Pat. No. 5,631,190 to Negley entitled Method for Producing High Efficiency Light-Emitting Diodes and Resulting Diode Structures and U.S. Patent Application Publication 2005/0215000 to Negley entitled Etching of Substrates of Light Emitting Devices.